Setting up your Node.js environment is the first step toward building web applications using JavaScript on the server side. This tutorial will guide you through creating a simple Node.js application and configuring your development environment with Node.js, npm, and Express.js.

What is Node.js?

Node.js is a runtime environment that allows you to run JavaScript on the server. It uses an event-driven, non-blocking I/O model that makes it suitable for building scalable network applications.

What is npm?

npm, or Node Package Manager, comes with Node.js and allows you to install libraries and packages that enhance your application's functionality. It is essential for managing dependencies in your projects.

What is Express.js?

Express.js is a web application framework for Node.js that simplifies the process of building web servers and APIs. It provides a range of features to help you manage routes, handle requests, and serve static files.

Prerequisites

Before starting, make sure you have the following:

• A computer with internet access
• A code editor (e.g., Visual Studio Code, Sublime Text)
• Basic understanding of JavaScript

Step 1: Installing Node.js and npm

1. Download Node.js: Visit the Node.js website and download the latest version. The installer includes npm.

2. Install Node.js: Run the installer and follow the prompts. This will set up both Node.js and npm on your machine.

3. Verify Installation:

   • Open your terminal or command prompt.
   • Run the following commands to check if Node.js and npm are installed:

     node -v
     npm -v
     

   • Both commands should return version numbers, indicating successful installation.

Step 2: Creating a Simple Node.js Application

1. Create a Project Directory:

   • Navigate to the directory where you want to create your project.
   • Use the following command to create a new directory:

     mkdir my-node-app
     cd my-node-app
     

2. Initialize the Project:

   • Run the following command to create a package.json file, which will manage your project’s dependencies:

     npm init -y
     

   • This command creates a default package.json with basic information.

3. Install Express.js:

   • Install Express.js by running the following command:

     npm install express
     

Step 3: Building a Simple Server

1. Create the Server File:

   • In your project directory, create a new file called server.js.

2. Write Server Code:

   • Open server.js in your code editor and add the following code:

     const express = require('express');
     const app = express();
     const PORT = 3000;
     
     app.get('/', (req, res) => {
         res.send('Hello, World!');
     });
     
     app.listen(PORT, () => {
         console.log(`Server is running on http://localhost:${PORT}`);
     });
     

3. Explanation of the Code:

   • const express = require('express');: Imports the Express library.
   • const app = express();: Creates an instance of an Express application.
   • app.get('/', (req, res) => {...});: Defines a route that responds to GET requests at the root URL.
   • app.listen(PORT, () => {...});: Starts the server on the specified port.

Step 4: Running the Server

1. Start the Server:

   • In your terminal, run the following command:

     node server.js
     

   • You should see the message indicating that the server is running.

2. Access the Application:

   • Open a web browser and go to http://localhost:3000.
   • You should see "Hello, World!" displayed on the page.

Step 5: Making Changes and Restarting the Server

To make changes to your server and see them reflected without restarting manually, you can use a package called nodemon.

1. Install Nodemon:

   • Run the following command:

     npm install --save-dev nodemon
     

2. Update package.json:

   • Open package.json and modify the scripts section to add a start script:

     "scripts": {
       "start": "nodemon server.js"
     }
     

3. Run with Nodemon:

   • Now, instead of running node server.js, use:

     npm start
     

   • Nodemon will automatically restart the server whenever you make changes to server.js.

Conclusion

You have successfully set up your Node.js environment and created a simple web server using Express.js. With this foundation, you can explore building more complex applications. The next steps will involve expanding your application’s functionality, such as adding routes, handling data, and integrating databases. Keep experimenting and building to enhance your skills!